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A Few Questions About REDAlert

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Sam Roberts
A Few Questions About REDAlert
on Apr 6, 2009 at 5:40:03 pm

Hi Guys,

Nobody's answering this one over at RED User so I thought I give it a shot here.

A few questions regarding REDAlert:

Do the Zebra colors in RedAlert give the same exposure indications as the camera false color?
(0 to 108 IRE)

Beside the Zebra tab in REDAlert is the number 95%. Does this represent IRE?

Does it match the high zebra IRE that I can set in the camera? For instance if I change the top end IRE Zebra in the camera will REDAlert's Zebra IRE (if this is in fact what it is) change or is it fixed?

Thanks.


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Sam Roberts
Re: A Few Questions About REDAlert
on Apr 7, 2009 at 12:29:36 am

No answer here either? That's a first. Maybe if I rephrase the questions:

What do the different zebra colors in REDAlert represent?

What does the 95% number beside the Zebra tab in REDAlert represent?

Anyone?



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Graeme Nattress
Re: A Few Questions About REDAlert
on Apr 7, 2009 at 1:00:33 am

From what I remember, zerbra % in camera is in the range 0% through 109% from black through to full clipping. In REDAlert!, the range is 0% through 100% for full clipping.

Graeme

- http://www.nattress.com - Film Effects and Standards Conversion for FCP


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Uli Plank
Re: A Few Questions About REDAlert
on Apr 7, 2009 at 7:17:00 am

I think Graeme is right, and I suppose the colors don't mean a thing, they are just for identifying which one you are seeing.
I further suppose you are getting no answers because nobody is using them. Zebras are so "video", while RED is ETTR, I normally check the highlights with the small RAW column on the right side of the histogram.

Regards,

Uli

Director of the Institute of Media Research (IMF) at Braunschweig University of Arts


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Sam Roberts
Re: A Few Questions About REDAlert
on Apr 7, 2009 at 3:29:15 pm

Thanks guys.

Well Zebras are what RED calls them. I'm just wondering if the camera Zebras or False Color are related to what I see in REDAlert. In my experience the REDAlert Zebra black, red, green, blue, and yellow colors seem to represent about 92 to 110 at least that's what it looks like on my waveform but the 95% indication is puzzeling, it doesn't seem to have anything to do with anything.

I wonder if the zebra colors have something to do with the histogram? Although, if that's the case, why the black?......luminance maybe?

The lack of knowledge about REDAlert is I think is due to the fact that there is no manual- everyone's guessing.I wonder who wrote the program?



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David Battistella
Re: A Few Questions About REDAlert
on Apr 7, 2009 at 3:35:41 pm



Sam,

Just so you know. One of the guys who wrote the program has already responded in this thread.

RED ALERT was designed as a quick application to view and perform onelights on r3d files and that is what it does best. It's not supposed to be your final color correction tool.

I am not sure what you are trying to calibrate but there are better things to consider than the zebra's in RED ALERT. Testing, histograms, false color, and the many tools available on the camera is a much better way to figure out exposure on the RED ONE.

Check out my article on exposing for RED right here on the cow.

David






Peace and Love :)
Read my Blog
http://blogs.creativecow.net/DavidBattistella


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Noah Kadner
Re: A Few Questions About REDAlert
on Apr 8, 2009 at 7:19:42 am

Yeah it's like a one-light primaries quick grade room. If you are busting out the IRE and waveform you really should be in a more suitable color grading app such as Color or Scratch.

Noah

Check out my new RED Blog. Unlock the secrets of the DVX100, HVX200 and Apple Color.
Now featuring the Lens Adapter Guidebook, Sony EX1 Guidebook,
DVD Studio Pro and How to Light Interviews.
http://www.callboxlive.com


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Sam Roberts
Re: A Few Questions About REDAlert
on Apr 11, 2009 at 2:39:05 am

I don't get where you think I'm not using color, I never said that. I want to understand all my programs, which is difficult when some don't have a manual. I didn't ask for workflow opinions, I've been editing for over 25 years. I just want to know what the cross hatch colors in REDAlert mean.



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Russell Lasson
Re: A Few Questions About REDAlert
on Apr 11, 2009 at 5:06:10 am

Sam, as a bystander of this conversation, I don't think Noah was trying to attack your credentials.

I can see where you're coming from, wanting to make the most out of the applications that you have access to. I also think that REDAlert is a very useful app with some mysteries in it. I think your questions are valid.

On the other side of that, one reason why people are telling you to use other applications is because of the history of REDAlert. Maybe Graeme can correct me if needed, but my understanding is that REDAlert was written at a very early stage in the development of the RED ONE to simply interpret the footage to something useful. It received some updates, but for the most part, it's isn't intended to be a final product. Notice that it still says beta. I'm really not sure if there are plans to ever change that.

RED is letting everyone have access to the program for free, just to help out, even though it was originally intended as an internal development tool. They're not selling it or making money off of it. RED really isn't in the software business. They're leaving that to others to take care of. Since there are so many other options now, I'm not sure there is much incentive for RED to really invest a lot more into the program. So the chances to have RED write a manual for the application aren't great (unless you're volunteering).

In regards to your question, Graeme said REDAlert is based on 0% to 100%. 95% means that it puts the zebras at 95% luminance in REDAlert luminace units. You can change the 95% to be whatever value you want, though if you set them to 100%, they go way, but they do work if you put in 99.9%.




If I understand Graeme right, because the camera is based on a 0% to 109% luminance range, 95% on that scale won't match 95% in REDAlert because the maximum brightness is different, 109% in camera and 100% in REDAlert. The assumption that I'm making with this statement is that 109% in camera is equal to 100% in REDAlert. This might not be true, but if it is, then REDAlert 95% would equal 103% in camera (95% of 109% equals 103.55%).

I'm a post guy and don't have daily experience with setting up the camera, but if there is someone out there that would like to test this, go for it.

The problem with the whole conversation though is that there are so many other variables that impact how the footage is measured on set and how it is measured in REDAlert. Things like color space, gamma, exposure, curves, etc, all make this a potential moving target.

I'd just say, use the zebras in REDAlert to know when you're clipping your footage and make color decisions accordingly.

-Russ

And on a personal note, your previous post made you sound like someone who exercises a lack of control over his emotions. You might consider responding more professionally in the future. Just because this is a forum on the internet, doesn't mean you can talk to people differently than you would if you were speaking to them in person.

Russell Lasson
Universal Post
Ridgeline Digital Cinema Mastering
Salt Lake City, UT


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Uli Plank
Re: A Few Questions About REDAlert
on Apr 11, 2009 at 8:53:29 am

I think I can claim to know REDAlert pretty well, and it's a valuable tool in my workflow. I even wrote a few pages about it for my students, but these are in German (any volunteers for translating?).

But I still get the impression you don't fully understand it's role in the workflow. I never ever cared for the zebras, IMHO the most important tool in REDAlert is the histogram. It'll always tell me if I'm in danger to throw away valuable data during first-light, and that's all that's needed IF you want to work the ProRes route further downstream, since you'll reduce to 10 bit. Final grading is still left to Color with proper monitoring.

If you go offline/online (workflow no. 2 in the whitepaper), all you need is a decent look from REDAlert or no corrections at all if the look was OK in camera. It doesn't matter much anyway, since your footage will look different in FCP as long as Apple doesn't fix the gamma issues. Final grade is done in Color (or any other professional tool) from the sources anyway, nothing got lost, whatever you do in REDAlert.

So, with a high-end workflow, REDAlert is nothing more than a tool to simulate a look to check visually what you may get from your footage, no scientific measuring instrument. If you need high-end grading on site, you'll need a Scratch or any other serious RT-capable solution plus measuring instruments and calibrated monitors – very different league than a little preview app.

Hope this helps,

Uli




Director of the Institute of Media Research (IMF) at Braunschweig University of Arts


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David Battistella
Re: A Few Questions About REDAlert
on Apr 11, 2009 at 12:24:37 pm



Let's all just stop with this thread. I think it's beating a dead horse.

RECAP:
The cross hatch in RED alert is a warning signal that is not accurately displaying zebra according to what the camera sees. That should be enough to let us all know NOT to rely on cross hatch zebra patterns in REDalert, but to know that it means you are approaching clipping.

There are better tools within REDAlert to judge exposure.

David



Peace and Love :)
Read my Blog
http://blogs.creativecow.net/DavidBattistella


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gary adcock
Re: A Few Questions About REDAlert
on Apr 11, 2009 at 1:49:27 pm

[Sam Roberts] "I just want to know what the cross hatch colors in REDAlert mean. "

Sam

zebras are usually set in the camera monitor to allow the cameraman to be alerted when the exposure in an area is approaching the limit. These can be set to specific brightness settings both in the camera and in RED alert. Clicking on the number in RedAlert will allow you to increase or decrease that number to give you an idea on screen what your exposure is.

clicking on the zebra button turns them off.



gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows

Inside look at the IoHD
http://library.creativecow.net/articles/adcock_gary/AJAIOHD.php




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